Transcript Slide 1 - cgtechlab.us!

Routing and switching
Unit objective
 Explain the purpose and properties of
routing and switching
 Install and configure routers and
switches
Topic A
 Topic A: Routing
 Topic B: Installing routers and
switches
Internetworking devices
Ethernet hub
 Used to wire Ethernet star
 Operates at Physical layer
continued
Ethernet hub, continued
 Connects devices that use BNC or
RJ-45 connector
 Easy to configure
Repeaters
 Boost signal from one segment to another
 Two types
– Amplifier
– Signal-regenerating
Repeater placement
Wireless repeater
Repeater operation
 Physical layer
(OSI Layer 1)
 Amplifies signal
 Amplifies noise
 Limited in number
of repeaters per
segment
 Intelligent
repeaters
regenerate signal
and are immune to
attenuation
Limitations of repeaters
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Signal quality
Time delays
Network traffic
Node limitations
Activity A-1
Discussing internetworking basics
Bridges
Bridge operation
 Data Link layer
(OSI Layer 2)
– MAC sub-layer
 Transparent to
higher-level
protocols
 Filter traffic
based on
addresses
Bridge types
 Heterogeneous (translating)
– Can link between dissimilar MAC-layer
protocols
 Encapsulating
– Packages frames of one format into another
format
– Faster than translation
 Learning (transparent)
– Automatically identifies devices on segments it
connects
– Listens to replies and creates table of
addresses originating on each segment
Bridge routing management
 Two critical issues
– Need to know capacities of bridge
segments
– Need routing control to protect against
redundant messages
 Two common bridge routing
algorithms
– Spanning tree
– Source routing
Bridge filtering and intelligence
 Looks for other patterns within the
frame
 Uses patterns to selectively control
forwarding of frames
Local and remote bridges
 Local
– Has LAN link directly attached on each
side
– Comparable input and output channel
capacities
 Remote
– Links local network across wide area
segment
– Output channel usually has lower
bandwidth capacity than input channel
Layer 2 switch
 Also known as data switch or just
switch
 Operates at Data Link layer
 Divides network traffic based on MAC
addresses
 Functions like a hub, but learns MAC
addresses
Configurations for switched networks
Switched network with bottlenecks
Switched network without bottlenecks
Benefits of switches
 Each port is a separate collision domain
 Can direct traffic to only the port that the
destination computer is attached to
 Can connect dissimilar network
architectures
 Can support port-based authentication
 Can buffer packets in memory and resend if
a collision occurs
 Use port mirroring to monitor network traffic
Higher-level switches
 Multilayer switch (MLS)
– Operates at OSI layer 2 like a basic
switch
– Provides additional functions at higher
OSI layers
 Uses an application-specific integrated
circuit (ASIC)
 Operates at wirespeed
Managed Layer 3 switch
Virtual LAN
 Layer 3 filtering techniques enable
implementation of VLANs
 Segment large network into smaller
networks
 Each VLAN is a broadcast domain
 Switch controls broadcasts like a
router does
VLAN filtering
 Port-based grouping
– Certain ports can be assigned to specific VLAN
– Packets will be kept local to VLAN
 Address-based grouping
– Certain addresses can also be assigned to specific VLAN
– Packets will be forwarded only to appropriate VLAN
 Protocol-based grouping
– Switch can examine access protocol and forward packet
accordingly
 Subnet-based grouping
– Some switches might be able to identify appropriate
subnet and forward packet accordingly
VLAN trunking
 Modern switches have capability for
VLAN trunking
– Virtualize “n” number of network
adapters
– “n” has a theoretical limit of 4096
– “n” typically limited to 1000 VLAN
network segments
Trunking example
Activity A-2
Identifying types of bridges and switches
Routers
Router operation
About routers
 Protocol support
– Early routers supported a single protocol
– Today multiple-protocol routers support
15 to 20 protocols simultaneously
 Use tables to route traffic
– Static or dynamic
 Wide area links need:
– Flow control
– Multiple-path management
– Routing decision rules
continued
About routers, continued
 Wide area connection needs a routable
protocol
 Multiple (redundant) paths between
locations provides
– Backup
– Load balancing
– Full use of available bandwidth
 Use to subnet
– Increases security
– Reduces traffic congestion
 Includes programmable management
features
Router features
 Inclusion of processor, memory, and
storage
 Support for multiple physical interfaces
(ports)
 Support for multiple protocols
 Configuration and management
interface (open or proprietary)
Key points
 Router connects two or more subnetworks
 Router can be configured to support single
protocol or multiple protocols
 Router processes only packets specifically
addressing it as a destination
 Packets destined for locally connected
subnetwork are passed to that network
 Packets destined for remote subnetwork are
passed to next router in path
 Router that resides in same subnet as host
can be configured as default gateway
Types of routers
 Static
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Mostly replaced by dynamic
Manual configuration
Manual updates
Can’t compensate for changing environments
 Dynamic
– Use an Interior Gateway Protocol (IGP) to
communicate with each other
 RIP
 OSPF
 IGRP and EIGRP
 Path-vector protocols
 Default gateways
Routing table contents
 Destination network’s IP address
 Destination network’s subnet mask
 Router interface used to get to
network
 IP address of next router in path to
destination
 Number of hops to destination
Routing metrics
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Hop counts
MTU
Cost
Latency
Routing examples
 Local destination
 Remote destination, next hop known
 Remote destination, next hop
unknown
– Destroys packet
– Returns ICMP message
Brouters
 Operate at
– Network layer for routable protocols
– Data Link layer for non-routable
protocols
 Allow mix of routable and non-routable
protocols in a network
Bridges vs. routers
 Preference for routers in WANs
 Bridges can escalate transient
reliability problem into serious network
failure
 Routers don’t propagate broadcasts
 Remote bridges pass on all
broadcasts
 Network performance problems can
lead to broadcast storm
Activity A-3
Discussing routers and brouters
Topic B
 Topic A: Routing
 Topic B: Installing routers and
switches
Installing routers and switches
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Router configuration
Managed vs. unmanaged switches
Routing tables
NAT
PAT
VLAN trunking
Interface configuration options
PoE
Traffic filtering
QoS
Port mirroring
Diagnostics
Activity B-1
Discussing router and switch installation
Unit summary
 Explained the purpose and properties
of routing and switching
 Learned how to install and configure
routers and switches